Project Description The goals of the lipid mass spectrometry (MS) technological research and development program (TRD3) are to extend the study of ion chemistry and fragmentation mechanisms pioneered by M.L. Gross (Resource PI) and his staff specifically to biomedically important complex lipid molecules. Studies of lipid structures in TRD3 complement the biophysical studies in TRD1 by offering the opportunity to study protein interactions with lipids and membranes, including lipid-metabolizing enzymes. Lipid-protein and lipid-membrane interactions are relevant to the interactions of the signaling enzyme Group VIA PLA2 with membrane substrates, allosteric modifiers, and pharmacologic inhibitors (TRD1, C&S1, C&S2); to the recognition of lipid antigen-CD1 protein complexes by T cell receptors of Natural Killer T cells (DBP6); and to interactions of the Fatty Acid Synthase protein complex with subcellular membranes (DBP9, C&S3). TRD3 lipid MS technologies are integrated with TRD4 initiatives by providing the opportunity for complementary development of ESI-LIT-MSn with low energy collisionally activated dissociation (CAD) in parallel with MALDI-TOF-TOF-MS/MS with high energy CAD to provide overlapping but non-redundant structural information for classes of large stable biomolecules that are difficult to fragment under conditions of low energy CAD, such as glycan moieties of glycolipid antigens (DBP7), archaeal ether lipids useful in immunoadjuvant preparation (C&S4), and mycolic acids (DBP6, DBP7) that are potential diagnostic biomarkers. A unique feature of the WU Biomedical MS Resource is that MS technologies and expertise co-exist to conduct state-of-the-art studies of widely diverse molecular classes and create the opportunity to study interactions of molecular species as diverse as complex lipids and proteins.